A snapback-free reverse conducting IGBT with recess and floating buffer at the backside

抄録

We propose two novel ways to alleviate the reverse conducting insulated gate bipolar transistor (RC-IGBT) snapback phenomenon by introducing the floating field stop layer with a lightly doped p-floating layer and recess structure at the backside. The floating field stop layer is submerged in the N-drift region and located several micrometers above the P⁺ anode region, which would not degrade the blocking capability but can suppress the snapback phenomenon effectively. When the collector length exceeds 100μm, the snapback voltage V_SB of the floating field stop RC-IGBT with the p-floating layer can be less than 0.5 V. Furthermore, the recess structure at the backside can separate the N⁺ short and P⁺ anode region, which will be beneficial to eliminate the snapback. Finally, an RC-IGBT with a floating buffer layer and recess at the backside is proposed. Compared to the RC-IGBT featuring an oxide trench between the N⁺ short and P⁺ anode, the proposed one has utilized the simple recess structure to replace the costly oxide trench and achieved the identical characteristics simultaneously.